I'm checking a job that requires 480 volt 3 phase to a roof top heat pump unit for a gigantic industrial facility.
On the name plate it has MCA 65.68 (minimum circuit amps) then it has MOP 110 amps. On other units for the maximum overcurrent protection, I've seen "Max. ?? amps", but on this one it looks like it could go either way Max. or Min.
(MOP)
What would be your input as to which way this should go.
If I am calculting right according to the table for A/C and refrigerating equipment, it must be a "wound motor" and figured at 150% to get anywhere close to 110 amps if that is the max. And if you will refresh me on what breaker I would use at 110 amps since they don't make one for that. I think I would have to go down to 100 amps, but not too sure on this. I'm planning on using #4 thhn wire for the hots and the ground will be determined by the Max. overcurrent protection. Thanks for the input.
Also there are (2) 480/277 volt panels side by side. One panel takes the big thermal magnectic breakers, and the other one takes regular size breakers. Will it matter which panel I use? Thanks again.

Last edited by sparkync; 12/08/11 09:40 AM.